PURSE 2013

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Browsing PURSE 2013 by Subject "Acronychiapedunculata"

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    Antibiofilm activity of Acronychiapedunculata against methicillin-resistant Staphylococcus aureus
    (The University of Peradeniya, 2013-07-04) Nishya, M. R.; Bandara, B. M. R.; Parahatiyawa, N. B.
    Acronychiapedunculata (L.)Miq. (Rutaceae) is reported to display antimicrobial activity against a range of microbes. However, the effect of the plant extracts against infectious biofilms has not been described. We report the results of preliminary studies on the anti-adhesion activity of A. pedunculata extracts on the formation of biofilms by a clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA) and a standard strain of methicillin-sensitive S.aureus NCTC 6571. Air-dried powdered leaves and stem-bark of A. pedunculata were extracted into methanol using a sonicator (30 °C for 30 min) or a Soxhlet apparatus (65 °C for 24 h). The extracts were tested for antibacterial activity against S. aureus and MRSA using the agar well diffusion assay (well diameter, 9 mm). Minimum inhibitory concentration (MIC) values of the extracts were determined by the broth dilution method. Anti-adhesion activity was measured as colony forming units (CFU) by growing biofilms on a catheter tube in the presence of extracts at MIC values and culturing the viable bacteria present in the dislodged biofilms to form colonies on a Muller-Hinton agar plate. The plant displayed large zones of inhibition (S. aureus and MRSA) at relatively low concentrations of leaf (1.0 mg/ml) and stem-bark (0.7 mg/ml) extracts: 14-16 mm (sonicator extracts) and 17-18 mm (Soxhlet extracts). The MIC values were consistently lower for the Soxhlet extracts (2-64 ppm) than for the corresponding sonicator extracts (16-128 ppm). The MIC values of the stem-bark extracts (2-64 ppm) were lower than the corresponding values of the leaf extracts (64-128 ppm). The lowest MIC values were observed for the Soxhlet stem-bark extracts (4 ppm, S. aureus; 2 ppm, MRSA), and the highest MIC values were for the sonicator leaf extracts (64 ppm, S. aureus; 128 ppm, MRSA). The results show that the stem-bark extract prepared using the Soxhlet apparatus had the highest antibacterial activity. In the antibiofilm assay with MRSA, the CFU values were and in the presence ofSoxhlet stem-bark extract (at 2 ppm) and sonicator stem-bark extract (at 64ppm), respectively; the CFU values for the negative control (nutrient broth medium) and positive control (vancomycin, 1 ppm) were and , respectively. There was a reduction in the adherence of MRSA on the catheter tube at the MIC values of all the extracts. Further, the extracts showed higher anti-adhesion activity towards MRSA than S. aureus. However, increasing the concentration of the extracts did not always improve the antibiofilm activity